1FRY

THE SOLUTION STRUCTURE OF SHEEP MYELOID ANTIMICROBIAL PEPTIDE, RESIDUES 1-29 (SMAP29)

Summary for 1FRY

• Entry DOI: 10.2210/pdb1fry/pdb
• NMR Information: BMRB: 4643
• Descriptor: MYELOID ANTIMICROBIAL PEPTIDE (1 entity in total)
• Functional Keywords: random-ordered coil-loop, antimicrobial protein
• Total number of polymer chains: 1
• Total formula weight: 3266.04

Authors

Tack, B.F.,Sawai, M.V.,Kearney, W.R.,Robertson, A.D.,Sherman, M.A.,Wang, W.,Hong, T.,Boo, L.M.,Wu, H.,Waring, A.J.,Lehrer, R.I. (deposition date: 2000-09-07, release date: 2002-03-08, Last modification date: 2024-05-22)

Primary citation

Tack, B.F.,Sawai, M.V.,Kearney, W.R.,Robertson, A.D.,Sherman, M.A.,Wang, W.,Hong, T.,Boo, L.M.,Wu, H.,Waring, A.J.,Lehrer, R.I.
SMAP-29 has two LPS-binding sites and a central hinge.
Eur.J.Biochem., 269:1181-1189, 2002

PubMed Abstract: The CD spectra of SMAP-29, an antimicrobial peptide from sheep, showed disordered structure in aqueous buffers, and significant helicity in membrane-like environments, including SDS micelles, lipopolysaccharide (LPS) dispersions, and trifluoroethanol buffer systems. A structure determined by NMR in 40% perdeuterated trifluoroethanol indicated that residues 8-17 were helical, residues 18-19 formed a hinge, and residues 20-28 formed an ordered, hydrophobic segment. SMAP-29 was flexible in 40% trifluoroethanol, forming two sets of conformers that differed in the relative orientation of the N-terminal domain. We used a chromogenic Limulus assay to determine the EC50 of the peptide (the concentration that bound 50% of the added LPS). Studies with full-length and truncated SMAP-29 molecules revealed that each end of the holopeptide contained an LPS-binding domain. The higher affinity LPS-binding domain was situated in the flexible N-terminal portion. LPS binding to full-length SMAP-29 showed positive cooperativity, so the EC50 of the peptide (2.6 microm) was considerably lower than that of the individual LPS-binding domains. LPS-binding studies with a mixture of truncated peptides revealed that this cooperativity was primarily intramolecular (i.e. involving the N- and C-terminal LPS-binding sites of the same peptide molecule). CAP-18[106 -142], an antimicrobial cathelicidin peptide of rabbits, resembled SMAP-29 in that it contained N- and C-terminal LPS-binding domains, had an EC50 of 2.5 microm, and bound LPS with positive cooperativity. We conclude that the presence of multiple binding sites that function cooperatively allow peptides such as SMAP-29 and CAP-18 to bind LPS with high affinity.

PubMed: 11856344
DOI: 10.1046/j.0014-2956.2002.02751.x

Experimental method

SOLUTION NMR